So that got me thinking. How light could one get an f-body. According to the 9.5:1 weight to power ratio 200rwhp car weight 1900 lbs. It could be quite easy to turn, brake ect. that little weight on 275 tires and 14" willwood rotors. Shouldn't it? Can one get an f-body under 2000lbs?

I don't know, but brother-in-law pit crew and I have wondered when someone is going to bring a V6 to AI!

well i have gotten a 95 V8/T-56 car to 2800 under CMC limitations. w/ a V6/T5 and AI rules, i could easily see 2400 being a reality. whats stopping you from boosting power to match the weight if you cant get the weight to match 200 hp?
i'de find a 98 or newer car and use the stock brakes as they are just fine for my 3200lb CMC car (w/ driver). i would do it in CMC if they would cut the minimum weight to 3000lbs for a V6 (w/ driver).

What is the power to weight ratio in CMC? I was looking at the chart in the rules, 2800 looks off the chart, and if you just divide it looks like 13.7:1.
I also didn't see the 3000lb minimum for V6.

One could boost the power, but that was not my point. My logic being lighter is faster in corners, and undrer braking. Lighter being the same as heavier+power under acceleration. Furthermore, building something that weighs as much as a Honda challenge (or less), with twice the contact patch (big ol tires).

CMC is 3200 minimum w/ driver for 4th gens. i had one to 2800 w/out driver and ballast. car makes weight w/ driver and other legal add on's.
my only point was get it as light as you can. if you cant get it to where you want it, add power till your legal.
will you ever get a 4th gen to 2000lbs? if you do, there would not be much left that makes it a 4th gen. most likely will not be legal for AI @ that point.
BTW, V-6's are not legal in CMC.

Less confused now.
Anyway, I am not looking to part with my LS1 anytime soon, so no CMC for me. I was just wondering about AI possibilities.
So, my question still is, how light can a 4th gen get, if a 4 gen could shed all the weight it could shed?

Wow! I can't imagin a 4th gen getting to 2400 lbs, although I've never tried. Not knowing much about CMC or AI, what restrictions does AI not have to be able to shed 400 lbs? The V6 is going to be only 50-100 lbs (total guess) of that weight loss.

V6?? You don't need more than 4!!

Keep in mind Glenn's 2800 lb car actually is about a 3000lb car with a driver (AI weighs the car with driver, post race weight meaning all fluids yadda yadda yadda) That said, I'm sure that car could've lost another 4-500 lbs if you started using carbon body panels, lexan windows, etc. Some drivetrain components which can't be modified in CMC but can be for AI could also save weight such as tubular k-members, front suspension arms, torque arm, carbon driveshaft. You can completely chop the front off the car and build a tubular bumper/radiator support. I can see 2400lbs too.

I've mentioned this to folks in AI several times...but no one seems to care because no one has shown up with anything other than a v8. I think the day someone shows up with a featherweight Fox coupe with a 4 banger that rule will get changed

AI rules are here:

http://www.nasaproracing.com/rules/American-Iron-Rules.pdf

Anything that doesn't fall under these rules is subject to the NASA rule book (much larger file):

http://www.nasaproracing.com/rules/ccr.pdf

So, for AI see 6.1. There's no minimum weight for a 4 or 6 cylinder. Many have contemplated a 4 cylinder turbo Fox Mustang. You can get the Fox body pretty light (not sure how light) and the 4 cylinder doesn't weigh much. That doesn't help the Camaro crowd of course.

I have no idea the lowest a 4th gen could get. Ours is around 3000 empty. There's probably another 100 pounds in there, but I don't see much more than that. Maybe 2800 pounds as the lowest weight? But I'm just making that up based on my experience. I could be wrong.

Jason

Edit - So Al beat me to it. 2400 pounds? That's crazy! But I'd love to see it.

3rd gens came with 4-cylinders, although it was the horrible Iron Duke. Sneak a turbo ecotec in there though...

Do you think the Musturd 4 banger was any better? I rented a car with one of their auto V6 cars about five years ago and it could not get out of its own way - and I owned a Monza with an Iron Duke that was faster!

Neither motor is all that great, both of them are 60's/70's designs. Although the Ford 2.3L is pretty tough. I had a 2.0L in a 88 Ford Ranger (same family as the 2.3L) and man was that truck slow.

the more i think about it, the more i wish i had the ability/resources to do it myself.

in all seriousness, it almost sounds too good to be true....hhmmm..

The Mustang 2.3L is at least an engine that has been raced and was available in turbo configuration. It's also OHC which means it should breathe better than the pushrod 'duke.

So, yes, I do think the Mustake 2.3L was a better engine, at least in theory.

It's been done. Ted Schwartz in the OH-IN region ran a 4.3L Chevy in his '99+ Mustang for a while. Not sure the specifics on it, but he's got a 302-based motor in it now... that popped a head gasket at MAM on Sunday.

Just like the saying, it ran really well before it went though...

[edit] And my input on a really light AI car is that it would probably get run down at the end of long straightaways where aero is playing a bigger factor then weight. It is tempting to try it though...

i agree about the possibility of it getting run down in the straightaways. Right along with that, while the others are having to brake, would the v6 car with a severe weight advantage (and comparable abilities as far as brake setup/susp., etc.) be able to go so much deeper into the corner to maybe compensate?

the exit speeds it would be able to obtain might be advantageous enough so that the v8 cars, while having more power, might not be enough to compensate having to make up the speed they didn't have coming out of the corners and then their need to brake earlier into the next.

i'm sure on some courses the v6 AI car would shine more so than on others, but that's the gamble.

While we are on hypotheticals...

Drop a generation and save some weight. Start with a 3rd gen F-body. Can you put the 3.8/5sp in that and be AI legal? Seems to me you could get more lighter (is that a phrase? 'more lighter'? hehehe) with a 3rd than a 4th.

Costas
cars and such...

never read the AI rules...

Costas:

IIRC, the LS1 is a lighter motor then the 3.8L because of the aluminum block. I'll let someone else find the exact numbers though. Not sure if it's enough to negate the gain of having the weight set back farther though.

The idea I've been thinking about if I had an unlimited budget is one of the shorter 5.3L LSx motors out of a Grand Prix GXP. Obviously, I don't have an unlimited budget, so I haven't done much research, but I'm wondering if it's significantly shorter.

Even if you're over on horsepower, add a restrictor like the CMC guys and don't work the motor as hard.

the thing is, all V-8 cars have a minimum of 2800 in AI. if it was a V-6 or smaller, then there is no minimum. i'm thinking a turbo 6 from a 3rd gen or buick in a 4th gen chassis w/ the T5. hell, even the 4.3 V6 would be cool.

2800 with driver after a race is still damn light and probably as light as most (non-trust fund) people could afford to race one.

Once you start chasing those last 200+ lbs, it's going to start getting into megabucks. Do you really want to spend 6 figures to race for medals?

"How fast do you want to spend?"

Why a 4th gen chassis? I agree with Costas: 3rd gens are lighter to start with, so why bother dealing with a 4th gen? 3rd gens are cheaper to start with too!

I don't now 3rd gen's.
Is there is significan improvement in suspension design in a 4th gen vs a 3rd gen?
Are they pretty much the same car, different body?

Yea, you can actually work on a third gen (I've owned both, even built a race car out of a third gen once). The front suspension is a strut setup instead of the upper and lower a arms, but the cars handle well and it works. I'd start with a third gen and make it a Firebird body for better aero. We're down on HP (with a 6 cyl) and need all the help we can get.

i will not debate the advantage/disadvantage of 3rd gen/4th gen. i do like the 4th gen font suspension better.
as for weight. we have 3rd gens here that are bairly @ the minimum for CMC (3150) and i have built 2 4th gens now that have matched that weight, and need balast to get to thiers (3200) - w/ driver for both.

what i would like to see here is talk of thing to get a V-6 car down in weight w/in AI rules. things like VFN hood and hatch, lexan glass, carbon doors, K-member, and the cutting of any structure allowed that things like a cage (minimal to keep weight down) and subframe connectors would provide addequate stiffness for the chassis. the brakes could be left to 98 and up stock parts as the car would be light, no need for 4 pot fronts. i would cut out all the roof structure too and just keep the fiberglass skin in place.
i havent read the AI rules more than once and it was some time ago. i also realize what some have said about the cost of such a car like this. w/ a normal V-8 car, the HP would have to be matched w/ the weight, but not so w/ a V-6 car.
good debate, lets keep it going. V-6 cars can be had in good running shape here for under $3K.

I poked around to try to find out what an Lt1 and a v6 (whatever the engine designation is) from a 4th gen f-body weigh, but couldn't find anygood data. Anyone know?

Jason

Hood & hatch: legal
Lexan: legal
carbon doors: illegal
K-member: legal, if you can find one strong enough to trust

As far as cutting on the tub:

7.3 Frame
The entire tub, floorpan, firewall, and frame assemblies including the cowl and windshield frame must remain in the stock position and cannot be relocated. “Cowl” is defined as the metal structure installed by the factory between the firewall and base of the windshield. “Frame” and “framerail” are defined as the parallel boxed metal rails running the length of the car that form the basis of the unibody or frame. “Floorpan” is defined as the sheetmetal forming the floor and trunk floor of the car. Cars may not be “channeled” to raise the floor within the body or lower the body below the frame rails. The only modifications to these structures allowed will be in the following instances and no secondary purpose for a modification is allowed (i.e. electrical cable passage facilitating suspension clearance). If a modification is not listed below it is specifically not allowed.
a) To facilitate the addition of safety equipment such as subframe connectors and roll cage bracing (i.e. roll cage may extend through the firewall to strut towers);
To facilitate plumbing or electrical access.
c) To facilitate transmission fitment or access.
d) For installation of a fuel cell or fuel tank access. S197 chassis Mustangs may relocate the fuel tank from the rear seat stock location to the trunk area behind the rear axle.
e) For exhaust clearance. This does not allow exhaust components to be run through the firewall, which is not allowed.
f) To facilitate installation of and access to ignition and induction components in 4th generation F-body GM vehicles. Allowed modification is restricted to removal or clearancing of the cowl/wiper bucket area. The cowl and firewall must remain otherwise intact.
g) The floorpan may be modified for the purpose of facilitating the installation of a three-link type suspension. Such modification is limited to a hole being cut in the floorpan to allow the “third link” to pass through the floorpan to the attachment point in the cockpit. All components that intrude into the cockpit must be covered.
h) Rear framerails may be “notched” for suspension clearance in AIX only.
7.3.1 Radiator core supports may be removed or modified but frame rails must remain intact.
7.3.2 All cars must have OEM front and rear shock towers in the same location as stock. AI cars must utilize the OEM rear shock towers for rear shock attachment. Attachment of camber or caster adjusting devices is unrestricted. AIX cars must have OEM shock towers in place and resemble the factory build, but attachment points are free. The shock towers may be modified to facilitate suspension component fitment (i.e. SLA, etc) but must retain the general shape, structure and location as stock.
7.4 Body/Interior
7.4.1 Cars must have neat and clean appearances. All panels must fit properly and be free of sharp edges. All panels must be painted. No vehicle will be able to compete in more than one event with obvious body damage or unpainted body panels.
7.4.2 American Iron Extreme cars are unrestricted in all body panel material and modification. AIX cars are allowed to remove rear inner fender metal structures to facilitate tire fitment (“mini-tub”), but an alternative structure must be put in place to cover the tire and seal the tub assembly.
7.4.3 Only OEM (or the equivalent replacement of same type and material) body panels may used in the American Iron Class except as noted in Sections 7.4.4 and 7.4.7.
7.4.4 Composite hoods, hatchbacks, trunk lids, front fenders, fender flares, and bumper covers (fiberglass/carbon fiber, etc.) are allowed within the power to weight ratio constraints of the American Iron Class.
7.4.5 Acid dipping or body panel lightening is not allowed in the American Iron Class.
7.4.6 AIX vehicles may modify fenders for any purpose, but when viewed from above the top half of the tire must not be visible. AIX vehicles may use composite or other materials for the entire fender or quarter panel.
7.4.7 AI vehicles may modify wheel openings for the purpose of tire clearance only but when viewed from above the top half of the tire must not be visible. Composite (fiberglass/carbon fiber, etc) front fenders and rear fender flares are allowed.
7.4.8 All interior modifications (including removal of the dashboard and wiring) are allowed provided that the modifications do not conflict with any other rules contained herein or the NASA CCR. Dashboards may only be removed if acceptable replacements are installed (i.e. fabricated aluminum panels).
7.4.9 Lexan or polycarbonate material may replace windshield (3/16” min thickness for windshield), rear glass and side windows provided it is installed in accordance with the NASA CCR. Center bracing must be installed in the inside to support the windshield if Lexan is installed.
7.4.10 Spoilers and airdams are unrestricted but must be fixed for competition. Rear wings or rear spoilers installed on AI cars must not extend more than 1.5 inches beyond the outline of the rear bumper and not more than .75 inches on either side of the body when viewed from above.
7.4.11 All holes in floors and firewalls must be sealed according to NASA CCR.
7.4.12 All vehicles must start a race with a minimum of two functioning brake lights.
7.4.13 Hood and rear deck pins are recommended to secure the hood, trunklid, or hatchback.

Here's the whole rulebook:http://www.nasaproracing.com/rules/American-Iron-Rules.pdf



I'm not sure what you're saying here, but you still have to make the 9.5lbs/hp and 9lbs/ft-lb rules. So, assuming a 2600lb car race ready you could make 273hp and 288ft-lb.

Since we're now on the subject, is there an aftermarket, lightweight 4th gen hatch that I'm not aware of. We've already got lexan in ours, but it still weighs a ton!

Jason

SVO Mustang was the first thing I thought of when I read that in the AI rules long ago.

VFN offers a hatch for the camaro, it's a pin on and supposedly weighs 8#. The description says for steel car, so I assume that means a stock body.

I just found the page I wanted to reference earlier. Not sure how accurate these weights are as the page has been around for a long time and doesn't look like it's been updated recently.

http://www.bfranker.badz28.com/fbody/weights.htm

According to that page, the LS1 is only 30lbs heavier then the 3800II in standard trans form. The next part is purely speculation on my part, but my guess is that the LS1 is actually lighter (or at least break even) if you compared only engines, because the LS1 got the T56 and the 3800 got the T5.

While the 3800 would place the weight back further in the chassis, I'd guess a stock LS1 (294hp/311tq max) with a 2800lb race weight would be an interesting combo given the fat power band.

The fox chassis can be made very light, but the turbo 4 is not so much so. The Iron block SBC’s are a good 200# heavier then a plain old 5.0, those things are small and light, and the turbo four was a special version of the 2.3 cast in Lima that weighted within a few lbs of the 5.0.

I’ve seen V8 fox chassis in stripped down road race trim that were around 2650lbs with driver, so I wouldn’t be surprised to see a turbo 4 in the 2500-2600lb range.